[yabridgectl] Recursively prune empty directories

If pruning results in a directory becoming empty, then we should remove
that directory. This approach won't touch any directories that we aren't
pruning from.

CHANGELOG.md

@@ -96,6 +96,9 @@ Versioning](https://semver.org/spec/v2.0.0.html).
   makes it easy to switch from the 64-bit version of a plugin to the 32-bit
   version, or from a 64-bit version of yabridge to the 32-bit version. I don't
   know why you would want to do either of those things, but now you can!
+- If pruning causes a directory to be empty, then the empty directory will be
+  removed. This avoids having your plugin directories littered with empty
+  directories.
 - Copies of `libyabridge-vst2.so` and `libyabridge-vst3.so` are now reflinked
   when supported by the file system. This speeds up the file coyping process
   while also reducing the amount of disk space used for yabridge when using

tools/yabridgectl/src/actions.rs

@@ -451,11 +451,10 @@ pub fn do_sync(config: &mut Config, options: &SyncOptions) -> Result<()> {
             );
         }
 
-        // TODO: Prune empty subdirectories
         for file in orphan_files {
             println!("- {}", file.path().display());
             if options.prune {
-                match file {
+                match &file {
                     NativeFile::Regular(path) | NativeFile::Symlink(path) => {
                         utils::remove_file(path)?;
                     }
@@ -463,6 +462,15 @@ pub fn do_sync(config: &mut Config, options: &SyncOptions) -> Result<()> {
                         utils::remove_dir_all(path)?;
                     }
                 }
+
+                // If the directory `file` was in is now empty, then we'll also recursively prune
+                // the empty subdirectory
+                let mut parent_dir = file.path().parent();
+                while let Some(dir) =
+                    parent_dir.and_then(|dir| fs::remove_dir(dir).ok().map(|_| dir))
+                {
+                    parent_dir = dir.parent();
+                }
             }
         }